Harnessing the Immunogenic Potential of Gold Nanoparticle-Based Platforms as a Therapeutic Strategy in Breast Cancer Immunotherapy: A Mini Review

Enhancing breast Cancer immunotherapy using gold nanoparticles carrying tumor antigens

Cancer immunotherapy combined with standard treatments could provide an effective approach to enhancing anti-tumor responses. Activating antigen-presenting cells, such as dendritic cells (DCs), plays a central role in generating robust anti-tumor immune responses. Freund's adjuvant together with nanoparticles (NPs) and tumor antigens, promotes significant immune responses and shift antigen-specific T-cell activity from a Th2 to a Th1 response. Herein, Freund's adjuvant was combined with gold nanoparticles and tumor cell lysate (TCL). The AuNPs exhibited a spherical morphology. The in vitro release studies demonstrated a continuous and gradual release of AuNPs and TCL from Freund's adjuvant. The immunogenicity studies revealed high levels of cytokine secretion for IFN-γ, IL- 1, IL- 18, and TCD8+, along with reduced levels of IL- 4 cytokine in immunized mouse models in various treatment groups. In the prophylactic group, tumor growth was delayed, while in the therapeutic group, mouse models had more than 85% reduction within 31 days compared to the control group. The tumor size in the combination strategies, shrank to ~ 86% of its first size in just 17 days after treatment, while the control group tumor size increased by approximately 52%. These data suggest that the proposed drug system is an effective anti-tumor vaccine and also potentiate innate or adaptive immune responses for cancer therapy.

Immunomodulatory effects of metal nanoparticles: current trends and future prospects

The advent of nanotechnology has steered into a new era of medical advancements, with metal nanoparticles (MNPs) emerging as potent agents for precise regulation of the immune system. This review provides a comprehensive overview of the immunomodulatory roles of MNPs, including gold, silver, and metal oxide nanoparticles, in regulating innate and adaptive immunity. Additionally, we discuss the immunological effects of metal ions and metal complexes, offering a comparative analysis with nanoparticulate systems. We analyse cutting-edge strategies utilising MNPs to optimise vaccine efficacy, achieve targeted delivery to immune cells, and orchestrate inflammatory responses. Additionally, we discuss the therapeutic potential of MNPs in combating autoimmune diseases, cancers, and infectious agents, which is evaluated within the framework of precision medicine. Furthermore, we critically assess challenges such as biocompatibility, potential toxicity, and regulatory hurdles. Finally, we propose future directions for integrating MNPs with advanced delivery systems and other nanomaterials to propel the frontiers of immunotherapy. This review aims to provide a foundational understanding of MNP-mediated immunomodulation, inspiring further research and development in this burgeoning field.

Targeted intra-tumoral hyperthermia using uniquely biocompatible gold nanorods induces strong immunogenic cell death in two immunogenically 'cold' tumor models

Introduction

Hyperthermia is an established adjunct in multimodal cancer treatments, with mechanisms including cell death, immune modulation, and vascular changes. Traditional hyperthermia applications are resource-intensive and often associated with patient morbidity, limiting their clinical accessibility. Gold nanorods (GNRs) offer a precise, minimally invasive alternative by leveraging near-infrared (NIR) light to deliver targeted hyperthermia therapy (THT). THT induces controlled tumor heating, promoting immunogenic cell death (ICD) and modulating the tumor microenvironment (TME) to enhance immune engagement. This study explores the synergistic potential of GNR-mediated THT with immunotherapies in immunogenically 'cold' tumors to achieve durable anti-tumor immunity.

Methods

GNRs from Sona Nanotech Inc.™ were intratumorally injected and activated using NIR light to induce mild hyperthermia (42-48°C) for 5 minutes. Tumor responses were analyzed for cell death pathways and immune modulation. The immunogenic effects of THT were assessed alone and in combination with intratumoral interleukin-2 (i.t. IL-2) or systemic PD-1 immune checkpoint blockade. Immune cell infiltration, gene expression changes, and tumor growth kinetics were evaluated.

Results

THT reduced tumor burden through cell death mechanisms, including upregulated ICD marked by calreticulin exposure within 48 hours. By 48 hours, CD45+ immune cell levels were increased, including increased levels of immunosuppressive M2 macrophages. While THT led to innate immune cell stimulations highlighted by gene expression upregulation in the STING cGAS pathway and enhanced M1 and dendritic cell levels, tumor regrowth was observed within six days post-treatment. To enhance THT's immunogenic effects, the therapy was combined with intratumoral interleukin-2 (i.t. IL-2) or systemic PD-1 immune checkpoint blockade. Sequential administration of i.t. IL-2 post-THT induced robust CD8+ T-cell infiltration and led to sustained tumor regression in both treated and distant tumors, accompanied by the emergence of memory T cells. However, IL-2-induced immunosuppressive T-reg populations were also sustained to tumor endpoint suggesting that therapy could be further enhanced. Additionally, PD-1 expression, which was upregulated in CD8+ T cells by THT, was targeted with systemic PD-1 inhibition, further augmenting immune engagement within the TME.

Discussion

These combinatory treatments demonstrated synergistic effects, promoting durable anti-tumor responses and immune memory. Collectively, GNR-mediated THT effectively reduces tumor burden and remodels the TME, potentiating systemic immunity and enhancing the impact of complementary immunotherapies.

Simultaneous Down-Regulation of Intracellular MicroRNA-21 and hTERT mRNA Using AS1411-Functionallized Gold Nanoprobes to Achieve Targeted Anti-Tumor Therapy

Telomerase presents over-expression in most cancer cells and has been used as a near-universal marker of cancer. Studies have revealed that inhibiting telomerase activity by utilizing oligonucleotides to down-regulate the expression of intracellular human telomerase reverse-transcriptase (hTERT) mRNA is an effective method of achieving anti-tumor therapy. Considering that oncogenic microRNA-21 has been proven to indirectly up-regulate hTERT expression and drive cancer metastasis and aggression through increased telomerase activity, here, we constructed an AS1411-functionallized oligonucleotide-conjugated gold nanoprobe (Au nanoprobe) to simultaneously down-regulate intracellular microRNA-21 and hTERT mRNA by using anti-sense oligonucleotide technology to explore their targeted anti-tumor therapy effect. In vitro cell studies demonstrated that Au nanoprobes could effectively induce apoptosis and inhibit the proliferation of cancer cells by down-regulating intracellular hTERT activity. In vivo imaging and anti-tumor studies revealed that Au nanoprobes could accumulate at the tumor site and inhibit the growth of MCF-7 tumor xenografted on balb/c nude mice, thus having potential for anti-tumor therapy.

Immunization of Mice with Gold Nanoparticles Conjugated to Thermostable Cancer Antigens Prevents the Development of Xenografted Tumors

Gold nanoparticles as part of vaccines greatly increase antigen stability, antigen accumulation in the lymph nodes, and antigen uptake by antigen-presenting cells. The use of such particles as part of anticancer vaccines based on heat shock proteins to increase vaccine effectiveness is timely. We prepared and characterized nanoconjugates based on 15-nm gold nanoparticles and thermostable tumor antigens isolated from MH22a murine hepatoma cells. The whole-cell lysate of MH22a cells contained the main heat shock proteins. BALB/c mice were injected with the conjugates and then received transplants of MH22a cells. The highest titer was produced in mice immunized with the complex of gold nanoparticles + antigen with complete Freund's adjuvant. The immunized mice showed no signs of tumor growth for 24 days. They also showed a decreased production of the INF-γ, IL-6, and IL-1 proinflammatory cytokines compared to the mice immunized through other schemes. This study is the first to show that it is possible in principle to use gold nanoparticles in combination with thermostable tumor antigens for antitumor vaccination. Antitumor vaccines based on thermostable tumor antigens can be largely improved by including gold nanoparticles as additional adjuvants.